Illuminating means



May 12, 1942. H. EPSTEIN ILLUMINATING MEANS Filed July 29, 1938 ORNEY.

Patented May 12, 1942 UNITED STATES PATENT OFFICE ILLUMINATING MEANS Hirsch Epstein, Chicago, 111. Application July 29, 19a, Serial No. 222,013

This invention relates to illumination in gen- 9 Claims.

oral and, more particularly, to illumination by means of glow discharge devices.

It has been known that white light, such as is suitable for general room illumination, can be formed as a combination of two or more diflerent colored lights, and attempts have heretofore been made to provide two or more electric glow discharge devices of different color so correlated that the resulting color approaches that of natural light. Insofar as I am aware this has, heretofore, been generally unsuccessful. I have-discovered that by combining two different colored glow discharge devices the resulting light can be of a quality approaching that of daylight. It is an object of the present invention to provide an arrangement of this type for general room illumination.

In an apparatus for general room illumination it is undesirable to haveone continuous tube of In the construction of glow discharge devices of the above-mentioned character there is provided an electrode at each end of the tube. In those tubes of the prior art with which I am familiar the electrode constitutes a dark spot at the end of the tube. If the electrode is approximately two inches long. there will be a dark spot of-that magnitude at each end of each tube, or a dark spot of more than twice that amount between adjacent tubes. It is a further object of the present invention so to construct the respective tubes as to substantially eliminate the dark spot at the end of each tube. This result is obtained by providing a novel electrode arrangement so arranged that the glow passes from the part of the electrode adjacent the end suflicient candle power to provide a major portion of the light required, since if this is done then upon failure of the tube there is a loss of illumination for the entire room and, furthermore, the cost of replacement becomes excessive.

- In accordance with the teachings of the present invention I provide a number of tubes, each as a separate unit, which tubes are connected electrically in series, the number of tubes and the quality of light emitted from the respective tubes being such as to utilize the full load carrying capacity of the power supplying transformers and to give the correct quality of the light. The tubes are generally straight tubes and may be of any desired length. In one preferred construcries and supplied with power from a single transformer. It is one of the objects of the present invention to construct each tube in such a manner that it may be readily replaced by another tube in the event of failure. It is a further object of the present invention to construct each tube in such a manner that in the event of failure of any one tube it will automatically short circuit itself or perform an equivalent function whereby current may continue to fiow to the remaining tubes in series. Thus the failure of one out of twelve tubes in series will result in a diminution of approximately eight per cent of the light intensity. Furthermore, if the room in question is provided with more than one series of twelve tubes a failure of one of the tubes in one of the series will result in even a smaller change in total illumination.

of the tube rather than from the part of the electrode remote from the end of the tube.

It is a still further object of the present invention to provide glow discharge devices of the above mentioned character with terminal clips at the ends thereof so arranged that a tube can be connected in circuit or removed from circuit by. a simple manipulation no more complicated than the insertion of an ordinary electric light bulb in its socket.

The attainment of the above and further objects of the'present invention will'be apparent from the following specification taken in conjunction with the accompanying drawing forming a'part thereof.

In the drawing:

Figure 1 is a fragmentary sectional view of a corner of a room illuminated by a system em- 7 bodying the present invention;

tion the tubes are each approximately five feet long, ten or twelve tubes being connected inse- Figure 2 is a diagrammatic view illustrating a layout of the-tubing for one'wall of the room of Figure 1;

Figure 3 is a longitudinal sectional view through a glow discharge tube embodying the principles of the present invention;

Figure 4 is a fragmentary sectional view taken along the line 4-4 of Figure3;

Figure 5 is a sectional view corresponding to Figure 4 and illustrating a modified construction;

Figure 6 is a fragmentary longitudinal sectional view of a portion of a tube embodying a modified form of short circuiting means;

Figure 7 is a fragmentary view illustrating still another form of short circuiting device; and

Figure 8 is an enlarged fragmentary view of the adjacent ends of two tubes that are conv nected in series.

Reference may now be had more particularly to Figures 1 and 2. In Figure 1 -there is shown a fragmentary portion of the top of a room illuminated by glow discharge devices constructed in accordance with the present invention. An interior wall of the room is indicated at l, and the ceiling at 2. Two parallel horizontal rows of glow discharge devices, indicated at 3 and 4, are mounted on the wall I at the desired distance from the ceiling, say approximately one foot from the ceiling. These tubes may extend entlrely around all of the walls of the room, a. number of tubes being connected in series and supplied with current from a single transformer.

The number of tubes in series is determined by the voltage and other characteristics of the transformer used. Each transformer feeds one series circuit, and the number of such circuits is determined by the size of the room, the number of tubes connected in series, and the lengths of each of the tubes. A diffusing glass. plate 5 is mounted in front of the glow discharge devices 3-4, preferably at an angle, and carries a reflector'G. The diffusing glass plate 5 forms a small cove for the glow discharge devices. If desired, the plate 5 may be made of materials other than glass and may be made entirely opaque, in which case all or a portion of the interior surface of the plate 5 would constitute a reflector to direct the light from the tubes towards the wall and ceiling of the room. Where the plate 5 is formed of glass it is preferable that corrugated glass be used with the corrugations extending both lengthwise and crosswise of the plate. The plate is mounted with the corrugations on the outside and the smooth surface on the inside to facilitate removal of dust that may accumulate on the plate. The corrugations diffuse the light and thus eliminate the straight'lines of light which would otherwise be visible through the glass.

, In Figure 2 there is illustrated, diagrammatically, a number of tubes connected in series and supplied with current from a single transformer. The tubes consist of the upper row 3 and the lower row 4, each row consisting of a number of tubes 88 connected in series. A glass sleeve or socket I0 is located between adjacent tubes and serves to maintain the series connection. At the end of the rows 34 there is provided a connecting clip l2 which has a socket for receiving the end of the tube in the upper row and a similar socket-for receiving the end of the tube in the lower row. The series connected tubesare supplied with current at suitable high voltage from a transformer l4. In order to produce white light, or light most, closely approaching daylight, the tubes used are of different colors. It has been found that the white light can be produced by a combination of orange-gold colored light and green light, both being of high intensity. Fluorescent tubing producing light of those colors may be used. Other combinations may be used. In order to obtain the best results the different colored tubes are preferably adjacent one another. For instance, the first tube in the row 3 may be of the type that emits an orange-gold light and the first tube of the. row 4, adjacent thereto, may be of the type that emits an intense green light. The second tube of the row 3 may be of the type that emits an intense green light and the second tube of the row 4 may be of the type that emits an intense gold light. This staggered relationship may be carriedjout throughout the length of the wall or, if desired, all of the tubes in either one of the rows may be of the type that emits light of one color and all of the tubes in the other row may be of the type that emits light of the complementary color. The two rows of tubing are sufliciently close together so that objectionable colored spots are avoided.

Reference may now be had more particularly to Figure 3. In this construction there is shown a glass tube 20 sealed at the ends 2| and 22 and having circular metallic thimbles or contact ferrules 2324 at opposite ends. A conducting wire 3 liextends through the glass seal 2| and is electrically connected to the ferrule 23. Within the tube the wire 25 is covered by a layer of insulation 26 and extends to and through a metallic electrode 21, being electrically and mechanically connected with the electrode 21 at the portion of the wire 28 which extends through the electrode. The electrode 21 is formed of the usual metallic electrode materials and is of a shape well known in the art. It is circular in cross section and generally of the shape of a small diameter tube sealed at the end through which the conductor 28 extends. The electrode is mounted with its open end facing towards the adjacent end 2| of the glass tube. The outside of the electrode 21 is coated with a layer of insulation 29, of glass or the like. The electrode construction 30 at the opposite end of the tube 20 is substantially the same as the construction 21 above described. A sealed glass tube 3| joins the two electrodes mechanically. The glass tube 3| is sealed from the interior of the tube 20. A disc 32 of insulation is located in the tube 3| at either end or at the center thereof. The insulator disc 32 may comprise a thin sheet of mica. or the like. The wire 25 extends through the tube 3| to a position adjacent the disc 32, but not through the disc 32. Within the tube 3| the wire is coiled, as indicated at 34, and carries an iron or other magnetic member 35 adjacent the end of the wire. The wire 40 which extends from the ferrule 24 is also insulated within the electrode 30 and is also connected electrically with the electrode 30 and also extends through the tube 3| to the disc 32. The wire 40, is, however, not provided with a coil arrangement 34, as is the wire 25. The two wires terminate on opposite sides of the insulating disc 32 and are thus insulated from one another by that disc. thetube 20 by a plurality of perforated insulating discs 42 of a construction shown more particularly in Figure .4. The discs 42 fit within the tube 20 but do not constitute an obstruction within the tube. To effect this result the discs 42 are provided with perforations 43 constituting a large part of the area embraced by each disc.

An explanation will now be given of the manner of constructing the glow discharge tube illustrated in Figure 3. A solid imperforate disc 32 of mica or other insulation is inserted into a glass tube 3| preferably adjacent one end thereof since that may be more conveniently done than to locate it at the center of the tube 3|. Thereafter a wire 40 is inserted into one end of the tube and the wire 25 into the other end, so that the ends of the two wires are pushed into engagement with the disc 32 and maintained in engagement therewith by the spring 34. Thereafter the glass of the tube 3| is heated at the ends to seal the Wire within the glass tube. The discs 4242 for supporting the tube 3| are then strung upon the tube. The electrode 2'! is strung upon the wire 25 either before or after the wire has been passed through the tube 3|.

The tube 3| is supported within An electrical connection is established between the wire and the electrode in any desired manner, as for instance, by making a press fit, or by spot welding the wire to the electrode. Thereafter the glass coating 29 on the outside of the electrode 21 is fused into an integral structure with the glass 3|. A piece of insulation 26 is then slipped over the ends of the wires 25 and 40 if the wires are not otherwise insulated. The entire assembly, including the tube 3| and the contents thereof, the electrodes at opposite ends of the tube, and the discs 42, is then strung into the open ended tube so that the discs 42 support this assembly within the tube 20. At least one end of the tube 20 is then fused to seal the same, with the wire extending through the body of glass 2|. The brass or other electric conducting ferrule 23 may then be secured in place over the end of the tube and in electrical contact with the wire 25. seal is formed at the opposite end of the tube, except that some opening is left for evacuation, either at the end or elsewhere. The tube 20 is evacuated before sealing of the entire tube. During the pumping process of the tube it may be necessary to apply a high voltage to the wires 25-40 through the ferrules or thimbles at the ends of the tube. In order to prevent an electric break-down across the disc 32 between the ends of the wires 25 and on opposite sides of the disc, the end of the wire 25 adjacent the disc 32 is pulled away from the disc, against the action of the spring 34, during the pumping process. This is accomplished magnetically by slipping a coil of an electro-magnet over the tube 20 and energizing the coil to pull the iron member 35 and with it the end of the wire 25, away from the disc 32 to increase the gap between the wires on opposite sides of the disc 32. Later, upon deenergizing the magnetic coil 45, the end of the wire 25 springs back into engagement with the disc 32 under the action of the spring 34. Evacuation is continued while the tube is under high voltage, or electric bombardment, until the desired vacuum is obtained. During the pumping process the electrodes 21-30 are at a considerable potential difference so that any discharge between the electrodes facilitates the evacuation. When the tube has been evacuated of air and a proper gas has been introduced thereinto at the proper pressure (below atmospheric) the opening through which evacuation was performed is sealed and the coil 45 having been removed, the tube is ready for use as a glow discharge tube.

The operation of the glow discharge device illustrated in Figure 3 is substantially as follows: When potential is applied to the terminals 23-24 that potential is conducted to the electrodes 21-30 so that the interior of these two electrodes are at the same potential difference as are the terminals 23-24. It is to be noted that the outside of the electrodes is insulated by the glass insulation 29. Any glow discharge that occurs will therefore be from the open ended interior of the electrode 21, along the length of the tube to the open ended interior of the electrode 30. Therefore the portion of the glow discharge tube 20 from the open end of the electrode 21 to the closed end thereof, which may be of one and one-half inches in length, is illuminated. If the electrode 2'! were facing in the opposite direction then the length of the tube 20 at the electrode would be dark. As a result of the present construction the dark spot in the A similar L tube extends only from the terminal or ferrule 23 to a point slightly preceding the adjacent end of the electrode 21 rather than to a point adjacent the remote and of this electrode.

During the normal functioning of the glow discharge device the short circuiting apparatus within the tube 3| has no function. This apparatus begins to function when a defect develops in the tube 20 rendering it impossible for the normal glow discharge between electrodes to take place. Consider the tube 20 as one of a number of series connected tubes. Assume that a leak or other fault develops in this one tube. This fault will momentarily create a break in the series circuit. As soon as this break occurs almost all of the voltage which is applied by the transformer H to the series of tubes is applied to the electrodes 23-24 of the defective tube so that the potential across its electrodes is many times the maximum potential rating of the tube. This potential is conveyed by way of the conductors 25 and 40 to the opposite sides of the disc 32. Since the disc 32 is comparatively thin itis unable to withstand that high voltage and therefore breaks down or punctures. Once the mica disc 32 punctures, a solid metallic circuit is established through that disc by way of the conductors which were on opposite sides thereof.-

This immediately short circuits the defective tube and thereby reestablishes a circuit through the series of tubes. All of the tubes except the defective one now light up, the defective tube being short circuited through the interior thereof. The defective tube may be quickly located because of the lack of a discharge therethrough and may be replaced when convenient.

While I have shown the safety short circuiting device 3| located centrally of the tube, this is not an indispensable part of the present invention since the tube 3| may be located off center within the tube 20, as is illustrated in Figure 5. In this construction the tube 3| is supported off center within the tube 20 by means of discs 42' which function as do the discs 42 of Figure 3. It is preferable to locate the tube 3| on the rear side of the tube 20 rather than on the forward side thereof. In the case of indirect lighting effect the maximum light of the tube is to be thrown upwardly and therefore when the tube 2| is located off center it is located adjacent the bottom of the tube 20 rather than adjacent the top thereof.

Reference may now be had more particularly to the construction shown in Figure 6 illustrating a modified form of short circuiting device wherein the tube 3| is entirely omitted. In this construction the wire 25, which is electrically and mechanically connected with the electrode 21 in the same manner as in Figure 3, extends longitudinally through the tube 20 and is insulated. The insulation may comprise a coating of insulating enamel. The end of the wire 40' extends through a disc 50 of mica or other insulation, which disc is provided with slots corresponding with the slots 43 of Figure 4 so that the disc 50 does not constitute an obstruction to the arc path through the tube 20. The wire 25' likewise extends through the disc '50 and is spaced from the wire 40 by a slight amount. During evacuation of the tube 20, in the pump? ing process, the end of the wire 25 is magnetically withdrawn from the disc 50, as heretofore explained. After evacuation of the tube 20 the end of the wire 25' is pushed through an open ing in the disc 50 by the spring 34, or the electromagnet, or both. The wire is provided with a magnetic disc which is also coated with insulating enamel, 'or otherwise insulated. A second disc 5| adjacent the disc 50 and of similar construction supports the end of the wire 25' when the same is retracted from the disc 50. The spacing between the ends of the wires 25' and 40' is sufficient to prevent flash-over between these wires during normaloperation of the tube. In the event that this tube should fail, and if it is one of a series of tubes, so that an excessive potential is immediately established between the ends of the wire 25 and 40' these two wires flash over and establish a permanent metallic short circuit through the tube.

In Figure '7 I illustrate another arrangement which permits the omission of the disc and the magnetic member 35. In this construction the wires 25' and 40' which are insulated along their entire length by a coating of insulating enamel or other insulation, are twisted together at their ends in such a manner as to avoid breaking the coating of insulation. This type of construction is applicable in tubes wherein the pumping is performed in such a manner as not to require the application of a high potential to the opposite electrodes during the pumping process. During the normal operation of the tube, when the normal potential is applied to the terminals thereof the insulation on the conductors 25a and 40a, which correspond to the conductors 25 and 40 of Figure 3, is insufficient to cause an electrical break down at the twisted ends 55. If this tube is one of a series and becomes defective so that the entire potential of the transformer exists between the wires 25a and 40a, the insulation around these wires is insufficient to withstand that potential and there is a break down resulting in a permanent fusion of these wires and establishment of a short circuit through the tube, thereby permitting the other tubes of the series to operate.

Reference may now be had more particularly to Figure 8 wherein I illustrate the means ID for electrically connecting the ferrules 23-24 of adjacent tubes. This means comprises an open ended tube or sleeve of an internal diameter such that the ferrules 23-24 fit snugly thereinto but are slidable therein. A metallic spring 6| maintains electrical connections between the ferrules and maintains the tubes 88 in position. The sleeve 60 is supported on the wall I in any desired manner, and supports the ends of the discharge tubes, the discharge tubes being easily slid into and out of the sleeve 60. If desired the sleeve 60 may be made of metal so that it serves to maintain electrical connections between the ferrules, in which event the spring 6| may, optionally, be omitted. 'If .the sleeve 60 is made of metal it is insulated on the outside, as by an oversized tubular sleeve of glass or the like slipped over the end of the sleeve 60 and the ends of the ferrules.

While I have shown an arrangement, wherein the white light is produced by different color producing tubes the same result may be obtained by tubes each of-which produces a white light, or any other colored effects may be produced.

In compliance with the requirements of the patent statutes I have here shown and described a preferred embodiment of my invention. It is, however, to be understood that the invention is not limited to the precise construction here shown, the same being merely illustrative of the principles of the invention. What I consider new and desire to secure by Letters Patent is:

1. An electric glow discharge device comprising a light-pervious tube of insulation closed at both ends and having an electrode adjacent each end, wire means extending from electrode to electrode within the tube and almost interconnecting the electrodes, there being a gap in the connection which gap is so small as to break down and establish a metallic connection from electrode to electrode upon application of an excessive voltage across the device and thus short .circuiting the same, and means for preventing Lil glow discharge along the surface of the wire and at the outer surface of the connected electrode, said means comprising a covering of insulation over said wire and over the adjacent portion of the electrodes and covering substantially the entire outer surfaces of the electrodes.

2. An electric glow discharge device comprising a. light-pervious tube of insulation closed at both .ends and having an electrode adjacent each end, means extending from electrode to electrode within the tube for short circuiting the same, and a covering of insulation over said means and over the adjacent portion of the electrodes and covering substantially the entire outer surface of the electrodes, each electrode being hollow and open at the end facing the adjacent end of the tube and closed at the end which faces inwardly of the tube.

3. An electric glow discharge device comprising a light-pervious tube of insulation closed at both ends and having a tubular electrode at each end, each electrode being hollow and open at the end facing the adjacent end of the tube and closed at the end which faces inwardly of the tube, and a covering of insulation over substantially the entire outer surface of each electrode.

4. An electric discharge device comprising a light-pervious tube of insulation closed at both ends and having a contact terminal at each end, a hollow electrode at one end of the tube, said electrode being open at the end facing the adjacent closed end of the tube and closed at its opposite end, a coating of insulation covering theentire outside of the electrode, conducting means connecting the electrode with the adjacent terminal, and a second electrode adjacent the opposite end of the tube.

5. An electric discharge device comprising a light-pervious tube of insulation closed at both ends and having a contact terminal at each end, a, hollow electrode at one end of the tube, said electrode being open at the end facing the adjacent closed end of the tube and closed at its opposite end, a coating of insulation coveringthe entire outside of the electrode, conducting means connecting the electrode with the adjacent terminal, and a second electrode adjacent the opposite end of the tube, said conducting means extending through the first electrode towards the other electrode in the path of the discharge.

6. an electric discharge device comprising'a light-pervious tube of insulation closed at both ends and having a contact terminal at each end, a hollow electrode at-one end of the tube, said electrode being open at the end having the adjacent closed end of the tube'and closed at its opposite end, a coating of insulation covering the entire outside of the electrode, conducting means connecting the electrode with the adjacent terminal, and a second electrode adjacent the opposite end of the tube, said conducting means aaaaaac extending through the interior of the first eleccent terminal, and a covering of insulation on the conductor within the first electrode.

7. An illuminating device of the glow discharge type comprising a light-pervious tube containing a gasof the type that produces a light-emitting glow upon the passage of an electric current therethrough, said tube being comparatively long'in relation to its diameter, and means for passing a current through the. gas'of the tube, said means including a tubular electrode open at one end and closed at the other, said electrode being mounted within and adjacent a closed end of the light-pervious tube and with the open end of the electrode facin the adjacent closed end of the light-pervious tube.

8. An illuminating device of the glow dis-; charge type comprising a light-pervious tube containing a gas of the type that produces a lightemitting glow upon the passage of an electric current therethrough, said tube being comparatively long in relation to its diameter, and means for passing a current through the gas of the tube, said means including a tubular electrode open at one end and closed at the other, said electrode being mounted within and adjacent a closed end of the light-pervious tube and with the open end of the'electrode facing the adjacent closed end of the light -pervious tube,- the entire outside surface of the electrode being of material which inhibits electron emission whereby the discharge emanates from the interior of the electrode and extends towards the adjacent closed end of the light-pervious tube and then around the outside of the electrode towards the opposite end of' the light-pervious tube.

9. An electric glow discharge device comprising a light-perv'ious tube of insulation closed at both ends and having terminals at opposite ends thereof, an electrode at each end of the tube con- 

